Anxiety and Phenylephrine Dosage

Overview

Spinal anesthesia is considered gold standard anesthetic technique of choice for cesarean delivery (1). However its use is frequently associated with maternal hypotension, which occurs in up to 71% of cases, without prophylactic treatment(2) Spinal hypotension can lead to unpleasant maternal side effects such as nausea, vomiting and dizziness. In addition, adverse effects on the neonate occur because of reduced uteroplacental blood flow resulting in impaired fetal oxygenation and fetal acidosis. As such, current research recommends the prophylactic use of vasopressors for improved maternal and fetal outcomes(3). The international consensus statement on the management of hypotension during cesarean delivery states, that a prophylactic phenylephrine infusion is superior to bolus administration and should be dose titrated according to blood pressure parameters (4). In according to the international guidelines, in our obstetric anesthesia unit, we use a standardized spinal anesthetic regime protocol with a standardized prophylactic phenylephrine infusion at a rate of 50 mcg/min, with the vasopressor dose titrated according to every minute blood pressure parameters. Spinal anesthesia causes maternal hypotension, resulting from a blockade of sympathetic efferent neurons. Patients with higher baseline sympathetic activation have been known to have more marked hypotension after spinal anesthesia (5, 6) Anxiety causes generalized sympathetic activation (7). In a previous research the investigators showed that preoperative anxiety assessed by VAS had a significant effect on hypotension after spinal anesthesia (8). Study objective: In this study the investigators aim to evaluate the effect of anxiety on the cumulative phenylephrine dosage in women undergoing cesarean delivery under spinal anesthesia with prophylactic phenylephrine infusion. The primary hypothesis is that parturients who suffer from preoperative anxiety measured by a verbal numerical scale (VNS) anxiety score and Spielberger State-Trait Inventory questionnaire, will receive higher cumulative doses of phenylephrine (resulting from higher incidence of maternal hypotension).

Methods: This is a prospective, observational, single center study, which will be conducted at the Rabin Medical Center (Beilinson campus), Petach Tikva, Israel, a tertiary university hospital. This study Is a purely observational study, with no implication on the medical treatment provided. Two hundred women aged 18 and above undergoing cesarean section delivery under spinal anesthesia will be enrolled after filling out an informed consent prior to surgery. Women will be requested to fill out an informed consent in the women's surgery waiting room on the day of surgery, when they aren't under any pain. The parturients preoperative anxiety will be assessed in the women's waiting room, on the day of the surgery using two previously validated direct psychological measures of anxiety: verbal numerical scale (VNS) anxiety score (9, 10), and the Spielberger. State-Trait Inventory questionnaire (13). Women will also be asked about nausea and vomiting during the surgery and in the post anesthesia care unit. In according to standard departmental clinical practice, baseline blood pressure will be determined in the preoperative holding area by recording 3 times ≥ 3 minutes apart using an automated oscillometric blood pressure cuff on the arm with the patient supine with left uterine displacement, with the mean of the 3 values taken as a baseline systolic and diastolic blood pressure. Women will undergo spinal anesthesia and blood pressure will be measured evert minute during labor. Hypotension will be treated by titrating the phenylephrine infusion and by phenylephrine boluses, using a standardized algorithm according to departmental protocol. At the time of spinal injection, a phenylephrine infusion will be started at 50 mcg/min. The automated blood pressure cuff will be programmed to cycle each minute. When each new blood pressure result will appear, the phenylephrine infusion will be adjusted based on the systolic blood pressure by a standard algorithm. Parturient's obstetric history, obstetric data and anesthetic data will be collected from each of the participant's medical file, in an anonymized way.